Evaluation of Ignition Timing Predictions Using Control-Oriented Models in Kinetically-Modulated Combustion Regimes Argonne National Laboratory

Format:

Conference/Event

Author/Creator:

Goldsborough, Goldsborough, author.

Contributor:

Johnson, Michael V.

McConnell, Steven S.

Smith, Timothy A.

Conference Name:

SAE 2012 World Congress & Exhibition (2012-04-24 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2012

Summary:

Knock integrals and corresponding ignition delay (τ)correlations are often used in model-based control algorithms inorder to predict ignition timing for kinetically modulatedcombustion regimes such as HCCI and PCCI. They can also be used toestimate knock-inception during conventional SI operation. Thepurpose of this study is to investigate the performance of variousτ correlations proposed in the literature, including thosedeveloped based on fundamental data from shock tubes and rapidcompression machines, those based on predictions from isochoricsimulations using detailed chemical kinetic mechanisms, and thosededuced from data of operating engines. A 0D engine simulationframework is used to compare the correlation performance whereevaluations are based on the temperatures required at intake valveclosure (TIVC) in order to achieve a fixed CA50 pointover a range of conditions. In this study engine speeds from 500 to4000 rpm are covered with fuel mean effective pressures (FMEP)ranging from approximately 5 to 70 bar. Two low temperaturecombustion schemes are utilized here, one which is fuel lean withatmospheric oxygen concentrations, and another which employsstoichiometric fuel-to-oxygen loadings but is diluted with variouslevels of EGR.It is noted that some features of each of the correlationsfollow the trends exhibited by the LLNL detailed toluene referencefuel (TRF) mechanism, however none is a good match under allconditions. The TIVC "operating maps"illustrate some similarities between the correlations, as well assome significant differences. A few correlations indicate theexistence of a TIVC "fall-off" regime,especially at higher fuel loadings, id est, boost pressures, due tothe influence of low temperature/NTC chemistry. This regimehowever, is diminished with high EGR due primarily to the reductionin oxygen in the system. Under many conditions covered in thisstudy a few correlations do a very inadequate job following thetrends of the LLNL TRF mechanism. This study demonstrates the needfor a robust correlation that includes low temperature/NTCchemistry, and is valid over a wide range of engine operatingconditions, as well as various levels of fuel reactivity, id est,octane number

Notes:

Vendor supplied data

Publisher Number:

2012-01-1136

Access Restriction:

Restricted for use by site license